textproduct: Rapid City

KEY MESSAGES

- Beneficial rainfall expected through Sunday.

- Cooler temperatures for Sunday through Tuesday, then a gradual warm up for the rest of next week.

UPDATE

Issued at 942 PM MDT Sat Jun 20 2026

KUDX radar shows a line of thunderstorms over Jackson and Bennett counties moving eastward toward the south central SD counties. These storms have been producing gusty winds under 40 mph and small hail and should exit the area in the next few hours. These storms are expected to remain below severe limits, especially as it shifts eastward toward more stable air. Water vapor imagery shows the series of upper waves still crossing near the MT/WY border approaching the forecast area. There is still good agreement that more showers (and iso T) will develop overnight...primarily across the NW to central SD plains where QPF totals could generally range from 0.10-0.50" by 12z...with some spots over half an inch. Could also see overnight fog across the parts eastern foothills. Chances for showers will continue through Sunday across the CWA as an 850mb low develops near the SD/NE border. Cool, easterly flow across the northern two-thirds of the state will keep showers going through the day...while higher theta E/instability south of a weak baroclinic zone could bring better chances of popcorn showers/isolated storms across Crook/Weston/Black Hills/SW SD counties Sunday afternoon. Severe weather is not expected. By the time the precipitation tapers off Sunday night, NW SD through central SD could see over an inch of QPF...possibly more than 1.5" in some locations.

DISCUSSION

(This Afternoon Through Friday) Issued at 1106 AM MDT Sat Jun 20 2026

Current upper-air analysis and water vapor imagery depict weak troughing over the Great Lakes region with a shortwave positioned over southern ID/western WY and an upper low over southern AB. Satellite imagery indicates increased WV and cloud cover over WY and the NE panhandle. Radar returns show that some early thunderstorms have formed over south-central SD and central NE, with some light showers over east-central WY. Surface observations show temperatures mainly in the 60s to low 70s, with dew points in the 40s across northeast WY and 40s to low 50s across western SD. Winds are generally southeasterly at 10 to 20kts gusting to 30kts across northeast WY and western SD. Gusty southeasterly winds up to 40kts will continue to develop over the SD plains, with the strongest winds over northwest SD.

Confidence in severe weather today is currently mixed due to increased cloud cover over much of northeastern WY and western SD as the shortwave approaches. The 12z HREF run still suggests conditions will still be leaning towards a moderate chance for severe storms over northeast WY, the Black Hills, and into far southwestern SD. SPC has moved the slight risk out of the region, leaving just the marginal risk for northeast WY and southwestern SD. There is a 2% tornado risk and 5% severe wind and hail risk for those areas. A possible landspout can't be ruled out over northeast WY. Storms will continue to develop late this morning/early afternoon across northeast WY and south-central SD. Multiple rounds of storms are expected to move through northeast WY into western SD throughout the afternoon and evening. The first round of storms may wipe out the environment, resulting in weaker storms during the second round. We will have to wait and see if the environment will be able to recover. The best chance for severe weather will still be southeast WY into the NE panhandle where conditions are more favorable.

Thunderstorms and showers will continue to move through the region into the overnight hours and persist into Sunday as the shortwave continues to move across the region. Severe weather is unlikely. QPF values through Sunday evening are still trending towards at least 0.50" for most locations, with higher amounts east of the Black Hills, where 1.00" to 1.50" is not out of the question. Temperatures will be cooler Sunday with highs ranging in the 60s to low 70s. Winds will also be on the lighter side.

Next week will start off cooler and wet as a cold front pushes through, bringing another round of showers to the region. Chances for precipitation will continue throughout the week as temperatures gradually warm up by the end of the week.

AVIATION

(For the 06Z TAFS Through 06Z Sunday Night) Issued At 1030 PM MDT Sat Jun 20 2026

Showers will redevelop late tonight into Sunday morning, especially across northwestern to central SD. Widespread MVFR/IFR conditions are expected in and near these showers. Areas of fog are also expected early Sunday morning, especially along the eastern foothills of the Black Hills. Some gradual improvement in flight conditions are expected Sunday night, but MVFR CIGS could linger into Monday.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.